<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box{
            height: 100px;
            width: 100px;
            background-color: pink;
        }
        /* 鼠标点击 */
        a:active .box{
            height: 200px;
            width: 200px;
            background-color: red;
        }
        /* 鼠标悬停 */
        a:hover .box{
            height: 100px;
            width: 100px;
            background-color: blue;
            border-radius: 50%;
        }
        /* 取消下划线 */
        a{
            text-decoration: none;
        }
        /* 给input框设置聚焦的样式 */
        input:focus{
            border: 2px solid red;
            color: red;
        }
        input{
            /* 输入框的默认样式(光标聚焦的时候) */
            outline: none;
            border: 2px solid white;
        }
    </style>
</head>
<body>
    <a href="javascript:void(0)">
        <div class="box"></div>
    </a>
    <input type="text" value="我是默认的文字">
</body>
</html>